1. Field of the Invention
The present invention relates to a washing machine, and more particularly to a washing machine which can generate a turbulent flow in a spin tub by upwardly impelling a washing water from a center of a lower portion of the spin tub.
2. Description of the Prior Art
As is well known, a washing machine is an appliance for separating dirt from articles to be washed such as clothing by sequentially carrying out various cycles in the order of liquid feeding, washing, rinsing, dehydrating, and draining cycles.
While the above cycles are being executed, dirt contained in the articles separates from the articles by means of friction between a liquid flow and the articles or by means of detergents.
FIG. 1 shows a conventional washing machine 100.
As shown in FIG. 1, washing machine 100 comprises a cabinet 110. An outer tub 120 is mounted inside of cabinet 110 for receiving a washing water therein. A spin tub 130 is rotatably mounted on a lower portion of outer tub 120 for receiving articles to be washed therein. Spin tub 130 is formed at a circumferential outer wall thereof with a plurality of apertures 135 so as to fluidly communicate with outer tub 120 therethrough. A motor 140 is secured to a predetermined position of an underside of outer tub 120, and a power transmission 150 is secured to a center position of outer tub 120 and receives a torque generated by motor 140 through a belt 145. Spin tub 130 is coupled to a first shaft upwardly extending from motor 140 so as to rotate while the dehydrating operation is being carried out. A pulsator 160 for generating a swirling flow is rotatably mounted at a lower portion of spin tub 130 and is coupled to a second shaft 154 upwardly extending separately from first shaft 152.
Pulsator 160 receives an oscillating torque generated by motor 140 which generates an oscillating torque in alternative directions through second shaft 154 so as to generate a swirl flow, thereby washing the articles.
A draining device 180 for draining the washing water in outer tub 120 is installed at a predetermined position of the underside of outer tub 120.
In washing machine 100 constructed as described above, a user tosses articles into spin tub 130 and adjusts a washing parameter such as a washing time and an amount of washing water to be supplied by adjusting a control panel(not shown). When a predetermined amount of the washing water is supplied into spin tub 130, motor 140 is actuated so as to transfer a torque generated by motor 140 to power transmission 150 through belt 145. At this time, power transmission 150 transforms the torque to a reduced rotational speed so as to rotate pulsator 160.
In brief, pulsator 160 is rotated by second shaft 154 so as to generate the swirl flow in spin tub 130, thereby washing the articles. While the washing and the rinsing operations are being carried out, pulsator 160 is alternatively rotated in clockwise and counter-clockwise directions.
Meanwhile, a plurality of rods 170 and a plurality of dampers 175 are provided in order to damp a vibration generated by a rotation of the articles and spin tub 130, and to uniformly apply the vibration to cabinet 110. Dampers 175 are installed at a lower portion of an outside wall of outer tub 120 spaced apart from each other, and each of rods 170 has a first edge portion connected to an upper portion of cabinet 110 and a second edge portion connected to each of dampers 175 so as to suspend outer tub 120 at cabinet 110.
In refrigerator 100 having the above-described structure, pulsator 160 rotates so as to generate the swirl flow in spin tub 130. The swirl flow ascends along an inner wall of spin tub 130 and descends from a center portion of an upper part of spin tub 130. Subsequently, the articles moving with the swirl flow are tangled with each other at the center portion of spin tub 130, thereby reducing a washing efficiency of washing machine 100.
To overcome the above-described disadvantage, washing machines which upwardly pump the washing water so as to prevent the articles from tangling in a center portion of a spin tub, thereby improving the washing efficiency, are disclosed. U.S. Pat. No. 4,402,198 issued to Cartier discloses a washing machine having an agitator for pumping a washing water. However, the agitator has a structure by which the agitator itself vertically moves, which results in making the structure complicated so that it is difficult to assemble the agitator into a washing machine.